As a conventional pedal device for an electronic piano, there has been known one disclosed e.g. in Patent Literature 1. This pedal device is comprised of a pedal box having an inverted U shape in cross section and fixedly mounted between left and right legs of the electronic piano, a frame having a U shape in cross section and accommodated in the pedal box, and three pedals mounted to the frame. Each of the pedal box and the frame has a front wall thereof formed with openings through which the respective pedals are inserted. Further, the frame has a rear wall thereof formed with engaging holes for engagement with the respective pedals.
Each of the pedals is formed by an elongated metal member extending in a front-rear direction, and has peripheral edge parts thereof somewhat extending downward to form a hollow open downward. In the rear end of the upper surface of the pedal, there are arranged an engaging piece and a screw in a manner adjacent to each other in the front-rear direction. The pedal is pivotally supported by the frame, with the engaging piece and the screw held engaged with the upper edge of the engaging hole of the frame from respective opposite sides. The pedal protrudes forward through the openings of the pedal box and the frame, and is pivotally moved downward about the engaging hole of the frame by a step-on operation by a player. Further, between the lower surface of the pedal and the bottom wall of the frame, there is disposed a coil spring for urging the pedal upward. The depressed pedal is returned to its original position by the coil spring.
However, in the above-described conventional pedal device for an electronic piano, since each metal pedal is directly mounted to the frame in a state in which the engaging piece and the screw are engaged with the edge of the associated engaging hole, the pedal cannot perform smooth pivotal motion, which makes it difficult to obtain a smooth pedal touch. Further, noise is apt to be generated in accordance with the pivotal motion of the pedal. For this reason, it is required to apply lubricant, such as grease, to the pivot of the pedal and parts associated therewith so as to eliminate the inconvenience. Further, it is necessary to form the engaging piece on the pedal and attach the screw to the same so as to mount the pedal to the frame, which increases the number of component parts and manufacturing man-hour, resulting in an increase in manufacturing costs.
As another conventional pedal device for an electronic piano, there has been known one disclosed e.g. in Patent Literature 2. This pedal device includes a pedal box, a pedal pivotally mounted to the pedal box, and a coil spring for returning the pedal to its non-depressed position. The pedal box is formed by a molded article made of a metal or a synthetic resin, as one-piece assembly which has two front and rear pedal mounting sections each having a front wall, a rear wall, and a top wall and formed into a downwardly-open inverted U shape in cross section, and a flat plate part connecting between the rear wall of the front pedal mounting section and the front wall of the rear pedal mounting section.
The front and rear walls of the pedal mounting sections are each formed with a rectangular pedal insertion window such that the pedal insertion windows are aligned in the front-rear direction. The rearmost pedal insertion window has a pivot protrusion protruding from the upper edge thereof. The frontmost pedal insertion window has a lower limit stopper protrusion protruding from the lower edge thereof and an upper limit stopper felt affixed to the upper edge thereof. The pedal has an inverted U shape in cross section and extends through the four pedal insertion windows. The pedal is pivotally supported by engagement with the pivot protrusion via a hole formed in the rear end of the pedal, and extends forward from the pedal box.
The coil spring is disposed below the pedal. The coil spring is mounted in a compressed state by inserting a screw from above through holes formed, respectively, in the top wall of the front pedal mounting section and the pedal and fastening a nut screwed onto the lower end of the screw. With this arrangement, when a step-on operation is started, the pedal is pivotally moved downward while compressing the coil spring, and comes into abutment with the stopper protrusion, whereby the lower limit position of the pedal is limited. When the step-on operation is completed, the pedal is pivotally returned upward by the spring force of the coil spring and comes into abutment with the stopper felt, whereby the upper limit position of the pedal is limited.
However, in this conventional pedal device, since the pedal is inserted from the front side into the pedal insertion windows each having closed four sides and aligned in the front-rear direction, it is required to form the pedal into a substantially linear shape, i.e. there are constraints on the shape of the pedal, and hence the degree of freedom is low. Further, when the pedal box is made of a synthetic resin, a portion of a mold is required to have a slide structure so as to form the pedal insertion windows shaped and aligned as above in the respective front and rear walls of each of the pedal mounting sections of the pedal box, which causes an increase in manufacturing costs. Furthermore, since the lower edge of the pedal insertion window against which the pedal abuts when it is stepped on is formed of the synthetic resin, the supporting strength of this portion is insufficient, which can cause deformation and the like problem. In addition, it is required to affix the upper limit stopper felt to the upper edge of the frontmost pedal insertion window having its four sides closed, and this gluing work is troublesome.
Furthermore, since the pedal is stepped on with a large force by a player's foot, the coil spring is generally configured to have a relatively large spring force. In this conventional pedal device, however, in mounting the coil spring, it is required to screw the nut onto the lower end of the screw inserted through the coil spring, etc. and fasten the same while compressing the coil spring against its large spring force, and hence it is very difficult to mount the coil spring.
The present invention has been made in order to solve the above problems, and an object thereof is to provide a pedal device for a keyboard instrument which makes it possible to stably secure a required action of a pedal, facilitate assembly thereof, and reduce manufacturing costs.
[Patent Literature 1] Japanese Laid-Open Patent Publication (Kokai) No. H09-212160
[Patent Literature 2] Japanese Laid-Open Patent Publication (Kokai) No. H09-305175